Tetrabenazine has been shown to improve gating of abnormal visual stimuli and improve postural stability in Huntington disease (HD) patients as measured by computerized dynamic posturography testing. This study aims to elucidate whether partial dopaminergic depletion via low dose tetrabenazine has a similar effect on masking out of abnormal visual stimuli on the Stroop interference test.

Participants will have Stroop Visual Interference Scores measured while OFF tetrabenazine for at least 3 days. Two doses of 12.5 mg tetrabenazine will be subsequently administered: first dose just after the Stroop test and second dose 3 hours later. Stroop Visual Interference Scores will be measured again in the ON state, 6 hours after the initial OFF measurement.

Tetrabenazine will be withdrawn for at least 3 days in Huntington disease patients currently taking the medication.

Drug: Tetrabenazine withdrawal

Tetrabenazine will be withdrawn for at least 3 days in Huntington disease patients currently on the drug. Patients will be examined via Stroop test in the OFF state. Two doses of 12.5 mg tetrabenazine will be introduced, spaced 3 hours apart. Stroop test will be performed 6 hours after initial OFF Stroop test.

Eligibility

Ages Eligible for Study:

18 Years and older (Adult, Senior)

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

Established diagnosis of Huntington disease by movement disorders expert

Patients currently taking tetrabenazine.

Patients should not have taken dopamine receptor blocking medication for at least three days

Exclusion Criteria:

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01834911